Question about Honeywell Programmable Thermostat Heater

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I had an old thermostat that i had to change need wiring diagram

I had the thermostat (old) was the seco control ta2000 and am now tring to change to a honeywell non programable thermostat the code is rth3100c can you give a wiring diagram to help?

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Both thermostatats will have terminal designators R,W,Y,G, possibly O/B, C, W1,W2, Y1, Y2, etc.
Simplest method is to remove wires from old stat one at a time. mark where they came from and then install at same desinated terminal on the new t-stat. Hope this helps. be sure to shut off power supply to the unit (furnace) first. The wire coming to the R (RH,RC) terminal is the 24 volt a/c hot, all others are feeding back to perform given function.

Posted on Dec 23, 2008

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E and AUX need to have a jumper wire to connect the two. W2 (white) goes to the AUX terminal with the jumper installed. Y to Y, G to G, O to O, R to R, X (probably blue), goes to C, but is optional since the RTH3100C has batteries.

Posted on Jan 03, 2013

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I want to change my old manual thermostat to a new programmable one. My old one has only two wires (black and white) with no labeling. How do I know where to connect on my new one thermostat?

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Reply back of any further questions.

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